avoid post urls without get
I understand the idea of not mixing controller function for multiple things. but I also think that having post urls, which cannot be get (even they do have a sensible meaning) is not nice. especially for the signup process, I would assume, that if you hit enter in the url bar, you would loose all data in the form, but still get to the same signup page. therefore i added the token as part of the url and the post goes to '/signup/:token'. when you get that url, you can restart signup with the same token.